This invention relates to stabilization of sodium percarbonate by coating it with an inorganic coating material.
Sodium percarbonate is used as a bleaching component in detergents, bleaches and cleansers in powder form. It is characterized by a good solubility in water and rapid liberation of hydrogen peroxide and it is environmentally acceptable since its decomposition products do not pollute the environment.
One disadvantage of sodium percarbonate is its relatively poor stability when stored in the presence of typical detergent components. For this reason, numerous measures have been suggested to improve the stability of sodium percarbonate by incorporating stabilizing additives therein and/or by coating the sodium percarbonate particles with stabilizing layers. In published German Patent Application No. DE 2,622,610, for example, a coating with an inorganic coating material of sodium sulfate, sodium carbonate and sodium silicate is proposed. Published German Patent Application Nos. DE 2,800,916 and DE 3,321,082 disclose coatings with materials which contain boron compounds.
Despite prior efforts to produce such products, there remains a need in the art for sodium percarbonate which exhibits improved stability.